[mips] Remove absolute size assertion for end directive

The .end <symbol> directive for MIPS marks the end of a symbol and sets the
symbol's size. Previously, the corresponding emitDirective handler asserted
that a function's size could be evaluated to an absolute value at that point
in time.

This cannot be done with when directives like .align have been encountered,
instead set the function's size to the corresponding symbolic expression and
let ELFObjectWriter resolve the expression to an absolute value. This avoids
a redundant call to evaluateAsAbsolute.

llvm-svn: 294012

lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp

@@ -915,10 +915,10 @@ void MipsTargetELFStreamer::emitDirectiveEnd(StringRef Name) {
   const MCExpr *Size = MCBinaryExpr::createSub(
       MCSymbolRefExpr::create(CurPCSym, MCSymbolRefExpr::VK_None, Context),
       ExprRef, Context);
-  int64_t AbsSize;
-  if (!Size->evaluateAsAbsolute(AbsSize, MCA))
-    llvm_unreachable("Function size must be evaluatable as absolute");
-  Size = MCConstantExpr::create(AbsSize, Context);
+
+  // The ELFObjectWriter can determine the absolute size as it has access to
+  // the layout information of the assembly file, so a size expression rather
+  // than an absolute value is ok here.
   static_cast<MCSymbolELF *>(Sym)->setSize(Size);
 }
 

test/MC/Mips/end-directive.s

@@ -0,0 +1,22 @@
+# RUN: llvm-mc -arch=mips -mcpu=mips32 -filetype=obj %s -o - | \
+# RUN:   llvm-readobj -symbols | FileCheck %s
+
+# Check that the assembler doesn't choke on .align between a symbol and the
+# .end directive.
+
+	.text
+	.globl	a
+	.p2align	2
+	.type	a,@function
+	.ent	a
+a:
+	addu	$2, $5, $4
+	.align 4
+	jr	$ra
+	.end	a
+$func_end0:
+	.size	a, ($func_end0)-a
+
+# CHECK: Name: a
+# CHECK-NEXT: Value: 0x0
+# CHECK-NEXT: Size: 24